uniform mat4 u_MVPMatrix;		// A constant representing the combined model/view/projection matrix.
uniform mat4 u_MVMatrix;		// A constant representing the combined model/view matrix.

attribute vec4 a_Position;		// Per-vertex position information we will pass in.
attribute vec3 a_Normal;		// Per-vertex normal information we will pass in.
attribute vec2 a_TexCoordinate; // Per-vertex texture coordinate information we will pass in.

varying vec3 v_Position;		// This will be passed into the fragment shader.
varying vec3 v_Normal;			// This will be passed into the fragment shader.
varying vec2 v_TexCoordinate;   // This will be passed into the fragment shader.

// The entry point for our vertex shader.
void main()
{
	// Transform the vertex into eye space.
	v_Position = vec3(u_MVMatrix * a_Position);

	// Pass through the texture coordinate.
	v_TexCoordinate = a_TexCoordinate;

	// Transform the normal's orientation into eye space.
    v_Normal = vec3(u_MVMatrix * vec4(a_Normal, 0.0));

	// gl_Position is a special variable used to store the final position.
	// Multiply the vertex by the matrix to get the final point in normalized screen coordinates.
	gl_Position = u_MVPMatrix * a_Position;
}